Soldering Party!

The next step for the Museum Without Walls project was building the 20 Refresh Rate modules and I quickly found that hand soldering all of them would be very time consuming. So I did what any reasonable person would do and drafted my friends to help. It turned out to be a lot of fun and we only messed up one board by soldering a chip in backwards (the culprit will remained unnamed). Thanks to Tom, Nick, and Sam for all coming and helping (most of the time :)). Below are pictures of our setup (we used a fan pointing backwards for "fume extraction" though it was more "fume displacement") and the box full of the finished boards.

PCBs Have Arrived!

It has been a while since I updated my blog but in that time the Refresh Rate Teacher project has progressed significantly. After searching for hobbyist friendly board houses, I decided to purchase custom PCBs from Seeedstudio's Fusion PCB service. I was not disappointed. Seeedstudio has incredibly reasonable pricing for custom PCBs which is normally not the case when ordering small batches. You must order in multiples of 10 from them but their pricing makes it totally worth it. To order 10 10x10 cm boards it was a mere $25 and only $4 dollars shipping! This is incredibly cheap compared to BatchPCB which Sparkfun endorses which would cost $48.75 for just one board! Check out their website for more details. They do require that your designs be open-source but that shouldn't be an issue for most hobbyists. The only downside to their service is the long wait (~3 weeks to receive your board). When I received the boards I was very pleased with their quality. I had ordered 20 boards and was pleasantly surprised to receive 24. I have since ordered more boards from them and again received 12 instead of 10. I don't know what this is due to but it's better than being shortchanged! Below you can find the pictures.

Refresh Rate Teacher v0.2

Success! After a few quick modifications, the module worked great. Well except for the one line that I haven't yet hooked up because I am using a 7 transistor darlington array instead of an 8 transistor version. I like the feel of the module in the hand but plan on cutting the corners in the final design to reduce the risk of the user cutting their hand on a sharp edge.

It works! (Mostly.)

Above are the images of v0.2 and as you can see there has been some basic reworking done to the board. First and most importantly I had to replace my original TO-92 78L05 with the TO-220 package because my circuitry required more than 100 mA which I had overlooked. Also I designed the board to be two sided, but because I can't do through plating at home I had planned on top-soldering. This turned out to be very difficult for some components. So I gave up on that and just soldered wire-wrapping wire in place of the top traces.

With this module, I finalized the code and thankfully included an ICSP header to program the board which made life a lot easier. After I got a basic design working I wrote a Processing sketch to upload new designs to my module via the serial connection.

Schematic for v 0.2

Board for v 0.2

The next step for this project will be to order the parts for the modules and then send out the board design to be manufactured. After all of that is done, I will finalize the design for the programmer and manufacture that.